This application claims Paris Convention priority of DE 102 19 175.1 filed Apr. 30, 2002 the complete disclosure of which is hereby incorporated by reference.
The invention concerns a motor vehicle headlight with an ignition device to generate an ignition voltage for operating an electric discharge lamp, and a safety device for protection from injuries caused by electricity, wherein the ignition device comprises a housing for accommodating the light, an ignition switch which can be connected to the light, and terminals for electrically connecting the ignition switch to the vehicle electrical system, wherein the housing can be mounted to a base plate.
Motor vehicle headlights of this type are known in the art. Operation of an electric discharge lamp (subsequently referred to as a light) requires the ignition device. When switched on, the ignition device subjects the light to an ignition voltage, which energizes the gas located in the light to emit light directly after being switching on.
Towards this end, the ignition device has an ignition switch, which generates the required high voltage when it is connected to the electrical system of the motor vehicle. The ignition switch is located in a housing and has terminals disposed on the housing for connection to the vehicle electrical system.
The housing also has a holder in which the light can be received and mounted. The holder is generally provided with contacts, which connect the mounted light to the ignition switch. To mount the ignition device with the light on the headlight, the housing can be mounted to a base plate disposed on the headlight.
DE 199 41 538 A1 describes such an ignition device, which comprises a safety device for protection against contact with electrically conducting leads during operation of the ignition switch.
Towards this end, the base of the light can be mounted in the holder on the housing. The holder and light have bayonet lock elements, which permit simple mounting of the light in the holder. The safety device comprises a lever, which cooperates with the bayonet lock elements of the light and the terminals on the housing such that the ignition device is separated from the vehicle electrical system when the light is removed from the housing. The terminals of the ignition switch on the housing are thereby separated from those of the power line on the vehicle electrical system side when the light is removed from the holder. Voltage is consequently removed from the contacts on the ignition switch.
This device is disadvantageous in that the ignition device can be connected to the vehicle electrical system and can be operated when the light base holds the bayonet lock in the closed position. The ignition device can therefore also be operated when the housing is not mounted to the reflector, although the device may cause injury should it be operated separated from the reflector. If the ignition device is switched on in this case, injuries may occur through contact with unprotected electrodes having electric voltage or due to the high operating temperatures of the light.
It is the underlying purpose of the invention to eliminate the above-mentioned disadvantages and, in particular, to provide a motor vehicle headlight with improved safety for maintenance or repair works.
To achieve this purpose, one inventive solution provides that the safety device is disposed on the base plate and has means for mounting the housing, wherein the ignition device can be connected to the vehicle electrical system via the safety device only when the housing is mounted. Advantageously, the electric connection of the ignition device to the vehicle electrical system can be effected only when the housing is disposed on the base plate.
The safety device produces the connection to the vehicle electrical system as soon as the housing is disposed on the base plate. This prevents the ignition device and optionally the light mounted in the housing from being operated outside of the headlight reflector. Injuries during work on the headlight can thereby be prevented as could be caused by electric voltage or high temperatures during operation of the light.
The ignition device and/or the light cannot be touched when the housing is mounted and the safety device interrupts connection to the vehicle electrical system when the housing is removed from the base plate. Exposed parts which may have dangerous electric voltages when the ignition device is connected such as e.g. electrodes on the light or elements on the base or on the holder are always separated from the vehicle electrical system when the housing is not installed, since the safety device interrupts the electric connection when the ignition device is removed from the base plate. This eliminates danger from high voltage on the ignition device, since operation of the ignition device is not possible in this case.
Advantageously in accordance with the invention, there is no need for additional protection for the light, the holder or for the contacts connecting the light to the vehicle electrical system, since the light can be exchanged only when the housing has been removed from the base plate thereby separating the ignition device and light from the vehicle electrical system.
Injuries caused by the operating temperatures on the light can be largely prevented, since the light cannot be operated outside of the reflector. This advantageously improves safety.
If the housing of the ignition device is removed from the base plate e.g. for maintenance thereby permitting possible contact with the electrically conducting parts, the electric connection to the vehicle electrical system is immediately interrupted through removal of the housing from the base plate.
In a further inventive development, the safety device comprises a connection piece disposed on the base plate for connection to a power line on the vehicle electrical system side and for receiving the terminals connected therewith which contact the terminals on the housing when the housing is mounted in a plugging position. The connection piece permits simple mounting of the terminals on the vehicle electrical system side, which are connected to the power line, to the base plate. Advantageously, the terminals on the vehicle electrical system side are fixed by the connection piece when the housing is removed from the base plate and the ignition device thereby separated from the vehicle electrical system. During mounting, the housing is disposed on the base plate such that the terminals on the connection piece come into contact with those on the housing. The ignition device or housing are thereby connected to the vehicle electrical system and may be operated when the housing abuts the base plate.
When the housing is disposed on the base plate, the electrically conducting parts are shielded from contact in an electrically protective manner. Contact with these parts is therefore prevented when the high voltage can be generated by the ignition switch and could consequently be present on some of the electrically conducting parts.
In an advantageous embodiment, the terminals comprise a plug-socket-arrangement, preferably a supply plug connected to the connection piece, which engages a corresponding socket on the housing for generating the electric connection. The terminals are thereby securely mounted in both the connection piece and in the housing and are preferably respectively integral therewith.
The invention provides for arrangement of the plug and socket such that they engage one another when the housing is disposed on the base plate in a plugging position. The housing can be rapidly and easily mounted and the design of the safety device is independent of the housing mounting.
The invention provides a supply plug integrated in the connection piece which is held by the connection piece on the base plate when the housing is removed from the base plate and the plug and socket are separated thereby interrupting the electric connection.
Advantageously, the plug and power line cannot be lost in the motor compartment of the vehicle during maintenance and mounting since they remain fixed to the connection piece and therefore to the base plate.
Arrangement of the power line at the vehicle electrical system side on the connection piece and its disposition on the base plate avoids the need for introducing the power line to the housing of the ignition device. The ignition device and housing can be compact, thereby advantageously gaining space in the front region of the vehicle.
The power line can thereby be guided on the reflector and the base plate can be sideward displaced from the cable bundle of the vehicle. A cable conduit may be provided on the connection piece through which the power line can be passed to the terminals on the connection piece at the vehicle electrical system side.
In one advantageous embodiment of the invention, the base plate is preferably formed in one piece and has an opening for insertion of the light on the rear side of the headlight reflector. The base plate thereby serves as the reflector rear wall. The base plate has an opening through which the light can be inserted when the housing is mounted. The opening is preferably disposed in the region of the optical axis of the reflector. This advantageously allows for compact construction of the headlight.
The invention further permits the housing to be disposed on and mounted to the base plate in one single motion, preferably through rotation about the optical axis of the reflector using a bayonet connection. This embodiment provides for a structure with which the ignition device and the light can be mounted to the reflector in a simple and inexpensive fashion. The housing is disposed on the rear side of the reflector for mounting and the light mounted thereto is passed through the opening to the optically active side of the reflector. At the same time, the terminals are connected and provide for the electrical contact between the ignition device and the vehicle electrical system. The ignition device is mounted with its housing to the base plate in one rotational motion, preferably about the optical axis of the reflector and defines a bayonet lock. For removal, the housing is turned in the opposite direction until it is released from the bayonet lock elements and can be removed from the base plate to separate the terminals.
Towards this end, the connection piece is movably guided in a guide on the base plate and securely held by holding means, preferably cams. In a preferred fashion, the guide on the base plate holds the connection piece when the housing is removed. The holding means prevent removal of the connection piece from the guide and the supply terminals remain connected when the housing is removed from the base plate.
During mounting of the housing on the base plate, the connection piece is moved in the guide in the turning direction of the housing. The invention thereby provides that the connection piece moves in the holding means in correspondence to the rotation during mounting of the housing. The guide is thereby fashioned such that the connection piece can be displaced in the guide by the housing.
The connection piece is thereby guided on the base plate, preferably about the optical axis of the reflector such that the terminals on the housing and on the connection piece remain fixed relative to each other and remain connected during mounting.
The terminals on the vehicle electrical system side are thereby connected to the connection piece with a movable and flexible power line such that the connection piece is held in the guide in a freely movable fashion.
Moreover, the holding means are designed to hold the connection piece in a mounting position when the housing is mounted and in a plugging position when the housing is removed. When the housing is mounted to the base plate it is held by the connection piece in a mounted position. The light is thereby fixed in the opening at a predetermined operating position. When the housing is dismounted and removed from the base plate, the connection piece remains arrested in the plugging position, preferably via cams. The terminals on the vehicle electrical system side remain in a predetermined position on the base plate via the connection piece i.e. in the plugging position and do not have to be repositioned for renewed mounting of the housing. The terminals can easily mutually engage when the housing is disposed on the base plate.
The invention permits construction of a motor vehicle headlight using a simple arrangement of the components, which can be mounted during production and maintenance in an inexpensive and safe fashion.
The invention is explained below with reference to the drawings.